Aspiration screening process for assessing need for modified barium swallow study

ABSTRACT

Whether a (stroke) patient is at risk for oral or pharyngeal dysphagia is determined by conducting a cough-based screening process for clinically evaluating the patient&#39;s swallow. The cough-based screening methodology is able to identify those patients who require a modified barium swallow test in order to rule out aspiration, and which patients do not need a modified barium swallow test. In accordance with the process the patient attempts to cough voluntarily. If the patient is unable to cough voluntarily, the patient is required to inhale an aerosol that stimulates a sensory innervation of the patient&#39;s larynx, thereby causing the patient to cough. The resulting cough is graded to determine whether the patient is at risk to a prescribed physiological condition, in particular pneumonia. The cough tests are supplemented by monitoring the ability of the patient to hold water in the patient&#39;s mouth for a prescribed period of time. If the patient is able to hold a prescribed volume of water in the patient&#39;s mouth for the prescribed period of time, the patient is permitted to be given a modified barium swallow test. If the patient is unable to hold a prescribed volume of water in the patient&#39;s mouth for the prescribed period of time, the patient is not permitted to be given a modified barium swallow test.

This is a continuation of application Ser. No. 08/885,360, filed Jun. 301997, now U.S. Pat. No. 5,904,656, issued May 18, 1999; which is acontinuation of application Ser. No. 08/559,562, filed Nov. 16, 1995,now U.S. Pat. No. 5,678,563, issued Oct. 21, 1997.

FIELD OF THE INVENTION

The present invention relates in general to the field of speechpathology, and is particularly directed to a process for determiningwhether a patient is at risk for oral or pharyngeal dysphagia, by meansof a cough-based screening process for clinically evaluating thepatient's swallow.

BACKGROUND OF THE INVENTION

In order to clinically detect those patients who are at risk foraspiration, speech pathologists currently employ a standard procedurefor evaluating a patient's swallow. A normal human swallow can beseparated into four phases: 1)—oral preparation, 2)—the oral phase,3)—the pharyngeal phase, and 4)—the esophageal phase. Patients who havesuffered a stroke, traumatic brain injury or neuromuscular disorder(such as MS or ALS) have an increased risk of aspiration, and may havedifficulty with either the oral phase, the pharyngeal phase or both,secondary to neurologic deficits. Poor tongue movement in chewing or inthe swallow can cause food to fall into the pharynx and into the openairway before the completion of the oral phase. A delay in triggeringthe pharyngeal swallowing reflex can result in food falling into theairway during the delay when the airway is open. Reduced peristalsis inthe pharynx, whether unilateral or bilateral, will cause residue in thepharynx after the swallow that can fall or be inhaled into the airway.Laryngeal or cricopharyngeal dysfunction can lead to aspiration becauseof decreased airway protection during the swallow.

An abnormal human swallow is termed dysphagia. The oropharyngealphysiology involved in a normal swallow is very complicated, and manydifferent neurological disturbances can disrupt normal swallowing andcan cause aspiration of food material, liquid or solid, into the lungs,leading to increased morbidity in hospitalized patients and possiblepneumonia. See, for example, the article by Jeri Logemann, entitled:“Swallowing Physiology and Pathophysiology,” Otolaryngologic Clinics ofNorth America, Vol. 21, No. 4, Nov. 1988, and the article by L. Kaha et.al., entitled: “Medical Complications During Stroke Rehabilitation,Stroke Vol. 26, No. 6, June 1995.

Speech pathologists have tried many procedures to detect or predictaspiration in patients with neurological deficits. Although the standardbedside swallow exam to screen patients is beneficial for evaluatingpatients at risk for oral or pharyngeal dysphagia, studies have shownthat, when compared to a modified barium swallow (MBS) videofluoroscopicexamination, it is neither very specific nor sensitive in detectingaspiration. See, for example, the article by Mark Splaingard et. al.entitled: “Aspiration in Rehabilitation Patients: ideofluoroscopy vs.Bedside Clinical Assessment; Archives of Physical Medicine andRehabilitation, Vol. 69, Aug., 1988, and the article by P. Linden, et.al., entitled” “The Probability of Correctly Predicting SubglotticPenetration from Clinical Observations”, Dysphagia, 8: pp 170-179, 1993.

As discussed in the above-referenced Logemann article, and also in anarticle entitled: “Aspiration of High-Density Barium Contrast MediumCausing Acute Pulmonary Inflammation—Report of Two Fatal Cases inElderly Women with Disordered Swallowing,” by C, Gray et al, ClinicalRadiology, Vol. 40, 397-400, 1989, videofluoroscopic evaluations aremore costly than bedside evaluations and videofluoroscopy is notentirely without risk. Because of the poor predictability of the presentbedside exams, the MBS is being used more and more with its increasedreliability for diagnosing aspiration. Many studies usingvideofluoroscopy have tried to pinpoint the exact anatomical orneurological deficit causing the dysphagia, as well as what stage of theswallow is primarily affected in different disorders.

Patients that have a head injury, stroke or other neuromuscular disordercan aspirate before, during, or after the swallow, and a high percentagecan be silent aspirators. Unfortunately, these patients might notdisplay any indication of aspiration during a clinical exam but can bedetected by the MBS, as discussed in the Logemann article and in anarticle by C. Lazurus et al, entitled: “Swallowing Disorder in ClosedHead Trauma Patients,” Archives of Physical Medicine and Rehabilitation,Vol. 68, Feb., 1987, an article by J. Logemann, entitled: “Effects ofAging on the Swallowing Mechanism,” Otolaryngologic Clinics of NorthAmerica, Vol. 23, No. 6, Dec. 1990, and an article by M. DeVito et. al.,entitled: “Swallowing Disorders in Patients with Prolonged OrotrachealIntubation or Tracheostomy Tubes,” Critical Care Medicine, Vol. 18, No.12, 1990.

The bedside swallow exam performed by most speech pathologists evaluateshistory, respiratory status, level of responsiveness and an oral exam.The oral examination includes a detailed evaluation of the muscles ofmastication, lips, tongue, palate, position patient tested in as well asthe swallowing evaluation. Sensation, various movements and strength arecarefully evaluated. In the pharyngeal stage, the patient is tested fora dry swallow, thin liquid, thick liquid, pureed textures and solidtextures.

A typical bedside exam looks for nasal regurgitation, discomfort orobstruction in the throat or multiple swallows, as well as any visiblesigns that may indicate risk for aspiration, gurgling, impaired vocalquality, and coughing. The bedside exam results are then analyzed todetermine whether the patient should have an MBS study to evaluateswallowing physiology and to rule out aspiration. Although the bedsideexam is very thorough, and can identify patients who are at risk for orhave dysphagia, it is not effective in determining which patients willaspirate.

In addition to the foregoing, speech pathologists have historically haddifficulty studying the sensory afferents of the larynx involved inairway protection. As described in an article by J. Widdicombe et al,entitled: “Upper Airway Reflex Control,” Annual New York Academy ofScience, Vol. 533, 252-261, 1988, the sensory afferents for generalcoughing travel the internal branch of the superior laryngeal nerve. Apatient may have a voluntary cough present with the efferent motorsystem intact, but not have any sensation on the larynx secondary to theafferents becoming completely or partially affected, which would beindicative of risk for silent aspiration.

As described above, the MBS test is of value to patients that silentlyaspirate. The difficulty arises in deciding which patients should havean MBS test. Not all patients with a closed head injury or a stroke willaspirate. Further, it is not economically realistic to evaluate allpatients with neurologic deficits for aspiration using an MBS test. Itwould be beneficial therefore to have a method to clinically screenpatients with neurologic deficits that have dysphagia, and to moreaccurately predict which patients are at risk of aspiration and whichpatients are not.

SUMMARY OF THE INVENTION

In accordance with the present invention, the shortcomings of theabove-described conventional processes employed by speech pathologiststo detect aspiration in patients with neurological deficits areeffectively remedied by a cough-based screening process which isoperative to clinically detect a (stroke) patient who is at risk foraspiration in both oral and pharyngeal phases of the human swallow. Theinventive screening methodology is able to identify those patients whorequire an MBS test in order to rule out aspiration, and which patientsdo not need an MBS.

The initial step according to the cough-based screening process ofpresent invention involves a pharyngeal test, in which the patient isgiven two separate tasks to perform. The patient will have beendiagnosed as having had a stroke, and is potentially scheduled toundergo a modified barium swallow (MBS) test. The patient should not beone with a history of asthma or on supplemental oxygen for dyspnea. Aspeech pathologist performs a preliminary general bedside swallowevaluation and also tests for cognition, voice quality and cranialnerves.

In the first step of the pharyngeal test the patient is required tovoluntarily cough. The patient's ability to voluntarily cough is areflection of the function of the patient's efferent motor system, andis graded by the testing pathological specialist as either normal ordecreased, if the patient is able to successfully cough. The patient maythen optionally be administered a water-holding test, in which thepatient is asked to hold a given amount of water in the patient's mouthfor a given period of time.

If the patient is not able to cough voluntarily, the patient issubjected to an inhalation cough test, in which a sensory innervation tothe patient's larynx is tested. As will be described, this sensoryinnervation test of the patient's larynx is carried out by stimulatingnociceptor (irritant) and C-fibre receptors, using an aerosolchemostimulant that is inhaled through the patient's mouth.

In accordance with a preferred embodiment of the present invention, theaerosol inhalant, which may be delivered by a standard aerosol inhaler,comprises an atomized solution of tartrate mixed with saline. Althoughother receptor specific chemostimulants may be employed, studiesinvolving inhaling tartate, reveal that tartrate will stimulate a cough100% of the time in normal individuals. Further, tartate is consideredsafe, does not cause pain or discomfort, and has not been shown to causebronchoconstriction or complications in asthmatics when inhaled in anaerosol form.

During the inhalation cough test, the aerosol stimulant is inject,edinto the patient's mouth by a respiratory therapist, using a nebulizerfor a relatively brief period of time. The patient is tested a maximumof three times at different stimulant strengths until a cough iselicited. During each successive stimulant application, the patientreceives progressively increasing concentrations of the aerosol for theprescribed period of time by tidal breathing at one minute intervalsusing successively increasing percentage concentrations.

In response to the patient coughing as a result of the inhaled aerosolstimulant, the inhalation cough test is terminated, regardless of thepercentage of concentrations used. The patient's response to theinhalation test is graded as either a low pneumonia risk (if the patientcoughs immediately in response to the initial aerosol spray and thecough appears strong or normal) or a high pneumonia risk (where thecough appears weak or the patient does not readily cough in response tothe initial concentration spray, but requires a more concentratedaerosol application).

Upon completion of the inhalation cough test, the water holding test isconducted. During the water-holding test, the patient is required totake two separate volumes of water into the mouth and hold the water fora specified period of time. Two separate volumes of water are used,since aspiration can occur with large volumes or smaller volumesseparately. During the water holding test, the patient is instructed notto swallow any of the water and, at the end of the specified time, toreturn the held water to a measuring receptacle. Any water that is lostout of the patient's mouth as a result of a facial droop or poor labialcontrol is collected and measured. Also, the total water returned to themeasuring receptacle is calculated, in order to determine if water mayhave spilled over into the pharynx should there be any of the originalvolume of water not recollected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of the cough-based screening process fordetermining whether a patient is at risk for oral or pharyngealdysphagia in accordance with the present invention;

FIG. 2 diagrammatically illustrates the use of an aerosol inhaler in theinhalation cough phase of the process of the present invention;

FIGS. 3-6 diagrammatically tabulate the results of conducting thescreening process of the present invention for individual ones of agroup of stroke patients;

FIG. 7 tabulates the results of the voluntary cough test of the presentinvention for forty stroke patients into normal and abnormal coughs,classified as no aspiration and penetration combined together versus anaspiration group;

FIG. 8 tabulates the results of the inhalation cough test of the presentinvention for forty stroke patients showing those diagnosed asdeveloping pneumonia and no pneumonia, classified as normal and abnormalgroups;

FIG. 9 tabulates the classification of MBS for two groups of strokepatients including forty patients who were able to perform and anadditional seven patients who were not able to perform the tests, interms of aspiration and no aspiration;

FIG. 10 tabulates multivariate association by stepwise logisticregression for no aspiration diagnosis;

FIG. 11 provides a matrix relationship between MBS aspiration (+) and(−) and a voluntary cough (+) and (−);

FIG. 12 tabulates Gold Standard ratio definitions; and

FIG. 13 provides a matrix relationship between MBS aspiration (+) and(−) and a voluntary cough/water test combined (+) and either or both nl.

DETAILED DESCRIPTION

As described briefly above, the steps of the cough-based screeningprocess of the present invention are operative to clinically detect a(stroke) patient, who is at risk for aspiration (one of thecharacteristics of dysphagia), by evaluating the patient for both oraland pharyngeal phases of the human swallow. The inventive screeningmethodology is able to identify those patients who require an MBS testin order to rule out aspiration, and which patients do not need an MBSfor that purpose. In addition, the invention quantifies the risk ofaspiration based on the results of the bedside screen test compared tothe MBS test.

Referring now to the flow diagram of FIG. 1, the cough-based screeningprocess according to the present invention begins with a pharyngealtest, shown at 100, in which the patient is given two separatephysiologic tasks to perform. Typically, the patient will be an adultindividual, who has been diagnosed as having had a stroke, has alreadybeen scheduled to undergo a (not yet administered) modified bariumswallow (MBS) test, and is able to follow commands and give informedconsent to participate. The patient should not be one with a history ofasthma or on supplemental oxygen for dyspnea. A speech pathologistperforms a preliminary general bedside swallow evaluation and also testsfor cognition, voice quality and cranial nerves.

The first step in the pharyngeal test 100 (STEP 101) is to ask thepatient to voluntarily cough. The patient's ability to voluntarily coughis a reflection of the function of the patient's efferent motor system,and is characterized or scored by the testing pathological specialist aseither normal, decreased or absent. If the patient is able tosuccessfully cough (the answer to query STEP 103 is YES), the patient'sresponse is rated in step 105 as either normal or decreased, dependingupon the testing pathologist's estimation of the cough response. Thepatient may then optionally be administered a water-holding test, shownat 300 and to be described, in which the patient is asked to hold agiven amount of water in the patient's mouth for a given period of time.

If the patient does not pass the voluntary cought test, namely, is notable to cough voluntarily or the cough is decreased (the answer to querySTEP 103 is NO), the voluntary cough is rated as absent or decreased,and the patient is then subjected to an inhalation cough test 200, inwhich a sensory innervation to the patient's larynx is tested. As notedbriefly above, this sensory innervation test of the patient's larynx iscarried out by stimulating nociceptor (irritant) and C-fibre receptors,using an aerosol chemostimulant that is inhaled through the patient'smouth. As diagrammatically illustrated in FIG. 2, during the inhalationcough test, the patient wears a noseclip 20.

There is increasing evidence that reflexes for cough andbronchoconstriction are mediated by different pathways, and there arenumerous chemostimulants which are receptor specific. See, for example,the article entitled “Regional Sensitivity of the Respiratory Tract toStimuli Causing Cough and Reflex Bronchoconstriction,” by J. Karlson et.al, Respiratory Medicine, 85 (Supplement A): 47-50, 1991, the text“Cough Receptor Sensitivity and Bronchial Responsiveness in Normal andAsthmatic Subjects,” European Respiratory Journal, 56: 291-295, 1992,and the article entitled: “Effects of Methacholine InducedBronchoconstriction and Procateral-Induced Bronchodilation on CoughReceptor Sensitivity to Inhaled Capsaicin and Tartaric Acid,” by M.Fujimura al., Thorax, 47: pp 441-445, 1992.

In accordance with a preferred embodiment of the present invention, theaerosol inhalant, which may be delivered by a standard aerosol inhaler,such as a commercially available Bennett Twin nebulizer, shown at 22 inFIG. 2, comprises an atomized solution of tartrate mixed with saline.Although other receptor specific chemostimulants may be employed,studies involving inhaling tartate, as described in the articleentitled: “Cough Receptor Sensitivity and Bronchial Responsiveness inNormal and Asthmatic Subjects,” by M. Fujimura et al, EuropeanRespiratory Journal, 56: 291-295, 1992, in the text entitled: “ClinicalToxicology of Commercial Products, Tartaric Acid,” Fifth Ed., p563,Williams and Wilkins, Baltimore/London, in the reference text entitled:“Martindale: The Extra Pharmacopoedia,” Twenty Ninth Edition, ThePharmaceutical Press, London, 1989, and in the above-referenced Lindenarticle have revealed that tartrate will stimulate a cough 100% of thetime in normal individuals.

Moreover, tartate is considered safe, does not cause pain or discomfort,and has not been shown to cause bronchoconstriction or complications inasthmatics when inhaled in an aerosol form. See, for example, thearticle by M. Fujimura et al, entitled: “Sex Difference in the InhaledTartaric Acid Cough Threshold in Non-Atopic Healthy Subjects,” Thorax,45: 633-634, and the previously referenced articles by M. Fujimura etal,. and the Williams and Wilkins, and Martindale texts.

During the first step (STEP 201) of the inhalation cough test 200, theaerosol chemostimulant is injected into the patient's mouth by arespiratory therapist, using nebulizer 22 for a prescribed period oftime (e.g., on the order of 15 seconds). The nebulizer output spray ratemay be on the order of 0.2 ml/min. as a non-limiting example. DuringSTEP 201, the patient is tested a maximum of three times at differentstimulant strengths until a cough is elicited. During each successivechemostimulant application, the patient receives progressivelyincreasing concentrations of the aerosol for the prescribed period oftime by tidal breathing at one minute intervals using successivelyincreasing percentage concentrations (e.g. 20, 50 and 80 percent).

Once the patient elicits a cough as a result of the inhaled aerosolstimulant in STEP 201, the inhalation cough test is terminated,regardless of the percentage of concentrations used. Next, the patient'sresponse to the inhalation test is graded in STEP 203 as either a lowpneumonia risk (as in the case where the patient coughs immediately inresponse to the initial aerosol spray) or a high pneumonia risk (in thecase where a cough is present but decreased, or the patient does notreadily cough in response to the initial concentration spray, butrequires a more concentrated aerosol application).

Upon completion of the inhalation cough test 200, the water holding test300 is conducted. As noted earlier, the water-holding test may also becarried out after or in parallel with the voluntary cough test 100,described above. In the water-holding test, the patient is required totake two separate volumes of water into the mouth and hold the water fora specified period of time (e.g. on the order of ten seconds). Twoseparate volumes of water are used, since aspiration can occur withlarge volumes or smaller volumes separately, as described in thepreviously referenced Logemann article.

During STEP 301 of the water holding test 300, the patient is instructednot to swallow any of the water and, at the end of the specified time(STEP 303) to return it to a measuring receptacle. The first volume ofwater given to the patient may be on the order of 15 ml, as anon-limiting example. Any water that is lost out of the patient's mouthas a result of a facial droop or poor labial control is collected andmeasured (STEP 305). In addition, the total water returned to themeasuring receptacle is calculated, in order to assess what water mayhave spilled over into the pharynx if any of the volume is missing. Inquery STEP 307, a determination is made whether the water holding testhas been conducted for two separate volumes of water. If the answer toquery STEP 307 is NO, a second vial of water is given to the patient instep 309, and the process returns to step 301. The second volume ofwater may be on the order of 30 ml, as a non-limiting example. If theanswer to query STEP 307 is YES, the process proceeds to query STEP 311.

In query STEP 311, based upon the results of STEP 305, a determinationis made as to whether the patient has passed the water-holding test,namely—no water has been lost out of the patient's mouth and no waterhas spilled over into the patient's pharynx. If the answer to query STEP311 is NO, it is concluded that the patient need not be given an MBStest. (In a test evaluation of performing the water test-holding teststeps on twenty normal individuals, ages 30-72, for both volumes, nochanges in volume return (p<0.01) were measured in STEP 305.) If,however, the answer to query STEP 311 is YES (there has been spillage orleakage from the patient's mouth), then it is concluded that the patientshould be given an MBS test.

EXAMPLE

FIGS. 3-12 diagrammatically tabulate the results of conducting theforegoing described methodology, using the component concentrations andvolumes of tartrate saline and water described above for a group ofstroke patients of the various ages listed. In the Figures, each (+)indicates that the patient failed the specified phase (voluntary cough,inhalation cough, water-holding test) of the process, while a (−)indicates that the patient passed that phase of the process.

In addition to the individual patient responses listed in FIGS. 3-6,FIG. 7 tabulates the results of the voluntary cough test for the fortystroke patients into normal and abnormal coughs, classified as noaspiration and penetration combined together versus the aspirationgroup.

FIG. 8 tabulates the results of the inhalation cough test for the fortypatients showing those diagnosed as developing pneumonia and nopneumonia, classified as normal and abnormal groups. It may be notedthat no patient who exhibited a normal cough response to this testdeveloped pneumonia.

FIG. 9 tabulates the classification of MBS for two groups of patientsincluding the forty patients who were able to perform and an additionalseven patients who were not able to perform the tests (for a total offorty-seven patients), in terms of aspiration and no aspiration.

FIG. 10 tabulates multivariate association by stepwise logisticregression for no aspiration diagnosis. FIG. 10 reveals no predictedprobablity of aspiration for any patient who passed the voluntary coughand water-holding tests.

FIG. 11 provides a matrix relationship between MBS aspiration (+) and(−) and a voluntary cough (+) and (−). Associated with the matrix ofFIG. 11 are the ratios of sensitivity (SENS), specificity (SPEC),predictive value of negative test (PVNT) and predictive value ofpositive test (PVPT), defined in accordance with the Gold Standard ratiodefinitions listed in FIG. 12.

FIG. 13 provides a matrix relationship between MBS aspiration (+) and(−) and a voluntary cough/water test combinted (+) and either or bothnl. Also associated with the matrix of FIG. 13 are the ratios ofsensitivity (SENS), specificity (SPEC), predictive value of negativetest (PVNT) and predictive value of positive test (PVPT).

As will be appreciated from the foregoing description, whether a(stroke) patient is at risk for oral or pharyngeal dysphagia is readilydetermined in accordance with the cough-based screening process of thepresent invention, which is able to identify those patients who requirea modified barium swallow test in order to rule out aspiration, andwhich patients do not need a modified barium swallow test. By requiringa patient who is unable to cough voluntarily to inhale an aerosol thatstimulates a sensory innervation of the patient's larynx, and therebycauses the patient to cough involuntarily, the patient can be graded todetermine whether the patient is at risk to pneumonia. Supplementing thecough tests with the water-holding test allows a determination ofwhether the patient is permitted to be given a modified barium swallowtest.

While we have shown and described an embodiment in accordance with thepresent invention, it is to be understood that the same is not limitedthereto but is susceptible to numerous changes and modifications asknown to a person skilled in the art, and we therefore do not wish to belimited to the details shown and described herein but intend to coverall such changes and modifications as are obvious to one of ordinaryskill in the art.

What is claimed is:
 1. A method comprising the steps of: (a) supplyingto the throat of a patient a medium that is effective to stimulate asensory innervation of the larynx of and thereby elicit an involuntarycough from an individual who does not suffer from a prescribed abnormalphysiological condition; and (b) identifying a risk of the patient tosaid prescribed abnormal physiological condition based upon a responseof the patient to said medium supplied to the patient's throat in step(a).
 2. A method according to claim 1, wherein step (a) comprisessupplying to the patient's throat a chemical that is effective tostimulate nociceptor (irritant) and C-fibre receptors in the patient'sthroat.
 3. A method according to claim 2, wherein said medium containstartrate mixed with saline.
 4. A method according to claim 1, whereinsaid prescribed abnormal physiological condition is dysphagia.
 5. Amethod according to claim 1, wherein said prescribed abnormalphysiological condition is aspiration.
 6. A method according to claim 1,wherein said prescribed abnormal physiological condition is pneumonia.7. A method comprising the steps of: (a) applying to the throat of apatient successive quantities of a chemostimulant that is effective tostimulate a sensory innervation of the larynx of and elicit aninvoluntary cough from an individual who does not suffer from aprescribed abnormal physiological condition; and (b) identifying a riskof the patient to said prescribed abnormal physiological condition basedupon a response of the patient to the chemostimulant supplied to thepatient's throat in step (a).
 8. A method according to claim 7, whereinstep (a) comprises applying to the patient's throat aerosols containingrespectively increasing amounts of said chemostimulant.
 9. A methodaccording to claim 7, wherein step (b) comprises identifying the patientto be at low risk for pneumonia as a result of an involuntary cough fromthe patient appearing normal in response to an initial application tothe throat of said patient of said chemostimulant, but identifying thepatient to be at high risk for pneumonia in response to requiring afurther application of said chemostimulant to elicit an involuntarycough, or as a result of said patient having a decreased or weakinvoluntary cough.